Fresh Air - Best Of: Nutritionist Marion Nestle / Science Writer Mary Roach

Episode Date: November 29, 2025

Food policy expert and nutritionist Marion Nestle's 2006 book, ‘What to Eat,’ became a consumer bible of sorts when it came out, guiding readers through the supermarket while exposing how industry marketing and policy steer our food choices. Now, two decades later, she's back with ‘What to Eat Now,’ a revised field guide for the supermarket of 2025. Also, film critic Justin Chang reviews the new film Hamnet.Science writer Mary Roach’s latest book, ‘Replaceable You,’ is about innovations in transplant medicine thanks to promising research and breakthroughs. She tells us about organs transplanted from pigs and attempts to replace bald spots on the scalp with hair from other parts of our bodies.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy

From W. H.Y.Y. in Philadelphia, this is Fresh Air Weekend. I'm Tanya Mosley. Today, nutrition policy expert Marion Nessel. Decades of studying the food industry have given her, as she puts it, a clear-eyed view of what we're up against every time we walk into a grocery store. The purpose of a supermarket is to sell as much food as possible to as many people as possible, as often as possible, at as higher prices they can get away with. I can't say that enough. Also, we hear from science writer Mary Roach. Her latest book, Replacable You, is about replacing human body parts, thanks to promising research and breakthroughs. She tells us about organs transplant it from pigs and attempts to replace bald spots on the scalp with hair from other parts of our bodies.

And she admits, if you're squeamish, she can sometimes be unpleasant to be around. So sometimes I can't sort of share my appreciation for all these. gooey bits and pieces of us that are performing miracles on a daily basis. And Justin Chang reviews the new film Hamnet. That's coming up on Fresh Air Weekend. Support for this podcast and the following message come from Dignity Memorial. When you think about the people you love, it's not the big things you miss the most. It's the details.

What memories will your loved ones cherish when you're gone? At Dignity Memorial, the details aren't just little things. they're everything. They help families create meaningful celebrations of life with professionalism and compassion. To find a provider near you, visit DignityMemorial.com. This is Fresh Air Weekend. I'm Tanya Mosley. My first guest is Marian Nessel, a molecular biologist turned nutritionist and food policy scholar whose voices helped decode for decades what we eat and why it matters. Her well-known book, What to Eat, became a consumer Bible of sorts when it came out. in 2006, guiding readers aisle by aisle through the supermarket while exposing how industry marketing

and policy steer our food choices. Two decades later, she's back with What to Eat Now, a revised field guide for the supermarket of 2025, where ultra-processed foods, plant-based meats, corporate organics, and our ability to have food delivered to our very doorstep have rewritten the rules. Nessle's journey began in the classroom. When she first began teaching a nutrition course in the early 70s, she says it felt like she was falling in love with the subject. She went on to serve as Associate Dean for Human Biology at the University of California, San Francisco,

and as staff director for nutrition policy at the Department of Health and Human Services, where she helped shape dietary guidelines for Americans in the 1990s. Nessel is the author of 15 books, including Safe Food, the Politics of Food, Safe Food, and soda politics. And Marian Nessel, welcome to fresh air. Oh, glad to be here.

Marian, I want to talk with you about this administration for a bit because RFK Jr. is at the HHS, talking about toxins and ultra-processed foods. Many of the issues that you also talk about, too, you guys seem to be aligned on many things. do you see a genuine opening here for food policy reform, even though he's in that role, and he's not in a role that is direct to our food issue in the United States? Well, I was very hopeful when he was appointed because he was talking about, let's get the toxins out of the food supply, let's make America healthy again,

let's make America's kids healthy again. Let's do something about ultra-processed foods. Let's do something about mercury and fish. And a lot of other issues that I thought, oh, how absolutely terrific that we're going to have somebody who cares about the same kind of issues I do. This is very exciting. And when President Trump introduced his nomination of Robert F. Kennedy Jr. on social media, President Trump talked about the food industrial complex. I nearly fell off my chair. I thought, here's the president sounding just like me. What's going on here? So then we had the first Maha report, the first Make America Healthy Again report, which talked about a lot of these issues and put in an aspirational agenda. We're going to work on this, this, this, this, this, and

this, all of that sounded terrific. And then the second report came out, and they had backed off on nearly all of the things that I thought were really critically important. You have been skeptical of his anti-vaccine rules. Oh, from the beginning. I'm a public health person. I see vaccination as one of the, well, first of all, I'm old enough that I remember what it was like when we didn't have vaccinations. You know, I remember what it was like to be a kid in the era of polio. You couldn't go swimming in the summer. You couldn't play with your friends in the summer.

It was terrifying, absolutely terrifying. You never knew when something absolutely terrible was going to happen and paralyze you for life. I remember what it was like before measles vaccines when kids were sick. Kids died, just like kids are getting sick and dying now. And to go back to that makes no sense to me at all. What were some of the things that were the most important to you that you felt like were dropped in that second run? Oh, marketing to children, reduction of ultra-processed foods, cleaning up food in schools, getting the toxins out of the food supply at the production level, and other kinds of things that there were things that had to do not only with health and human services, but also with, the Department of Agriculture and the Environmental Protection Agency.

But these things didn't happen. What did happen were declared Maha wins. And the Maha wins are companies voluntarily agreeing to remove artificial color dyes from their products, which I'm in favor of. I think that's great. but fruit loops with vegetable dyes are still fruit loops. M&Ms with vegetable dyes are still M&Ms. It's not going to make a big difference in the food supply.

On ultra-processed foods, they've said they want to define them, but that's all they've said. They're investigating the possibility of looking at marketing to children, but with no sense at all. that there are regulatory initiatives that they're considering. And they declared a big win when Coca-Cola said it would substitute cane sugar for high-fructose corn syrup, something that I termed nutritionally hilarious, because they're basically the same biochemically, and they're not going to make any difference at all.

If you want to reduce obesity in the United States and help people eat more healthfully, You've got to do things like change the agricultural subsidy structure. You have to stop the ability of food companies to market ultra-processed foods, especially to children. You need better school food. You need universal school meals. You need much more money in school meals than presently exists. You have to look for ways to make healthy foods an easier and less expensive. choice and look for every public policy that you can to do those kinds of things. And I don't see

that happening. You've worked inside of governmental agencies. So you kind of know a bit about how the machine works. What do you think happened between that first Make America Healthy Again guideline, a proposal, and the second one, why they were so drastically different, why the priorities changed in such a stark way? Well, they found out what lobbying was a about. You know, I mean, they were hit with, and there's a fair amount of evidence that they met with agricultural producers. They met with food industry representatives. And the food industry representatives and agricultural producers told them what the effects of these kinds of changes would be on the bottom lines of these industries. I'm sure they talked about job

losses. I'm sure they talked about having to move their businesses overseas. I'm sure They had all kinds of lobbying threats like that. I wasn't there. I didn't witness it, but I can assume that that's what happened because that's what always happens. Do you think that when it comes to public health, there seems to be, I don't know if you would call it like stratifying or siloing, like there are vaccines, there's food, there's medicine,

and why don't you think the government looks at it in a holistic way as a holistic approach. Well, because there's so many, there's so much private industry involved in this. And so much ideology, this is a government that has an enormous amount of ideology with some very ideology-based views of what public health is about.

You know, the idea that natural immunity is better than vaccination immunity or that fluoride is poisoning children or that seed oils are poisoning America or that high fructose corn syrup is poisoning America. I mean, these are not ideas that are backed by science. But we're in an era in which science is just considered just one way of looking at things

and people have different sets of facts that they believe, and this is part of food politics now in a way that's very troubling. We're listening to my conversation with Marian Nessel, a longtime food policy scholar, an author of What to Eat Now, her updated guide to navigating the modern supermarket, from ultra-processed foods to the politics behind what ends up in our carts. We'll continue our conversation after a short break. I'm Tanya Musley, and this is Fresh Air Week. So first off, I want to say your method.

You approach this book like an investigative journalist. You visited stores wherever you traveled. You interviewed managers. You make a point to say, though, that supermarkets are a business. They are not in the business of nutrition at all. And I think that when you say it out loud, it's, of course. But I think there may be maybe an implicit thing or a subconscious idea that I'm going to the grocery store. And there have been good choices that have been picked out for me for the good of,

of my health and nutrition, and not necessarily because it's about selling things. But there are some things that really set for us what we see when we walk into a grocery store, the things that are at eye level for us, like slotting fees. You call them suspiciously like bribes. Yes. What are slotting fees? Sorry about that. Well, what are they?

And how do they impact what we encounter when we walk in the grocery store? There are payments that food companies make to grocery stores to stock their products where people will see them. You know, there are rules about sales in supermarkets. The more products you see, the more you're likely to buy. Therefore, the products that are organized so that you cannot miss them are in prime supermarket real estate. And companies pay the supermarkets to place their products at eye level. At the ends of aisles, those have a special name, end caps, and at the cash register. When you see products at the cash register, they're paying fees to the supermarket by the inch of space.

And that's how supermarkets make a lot of their money is through slotting fees. And, of course, what this does is it keep small producers out because they can't afford to make those kinds of payments. Because these payments are pretty expensive. Very expensive. I mean, we're talking about thousands or in some cases hundreds of thousands of dollars. And every single product that is in a supermarket is placed where it is for a reason. There is research. I mean, what I can't believe and just can't get over is the amount of research that goes into it. The amount of consumer research, focus groups, a camera research, I mean, every, kind of social science research that you can think of is used to plot out how people are going

to walk through the stores, where the items are placed, what people are going to see, what they're most likely to buy. And what you want to do, of course, is you want to place the most highly profitable items where they're going to get the most viewers. And it's not, you know, the joke is, of course, if you want a bottle of milk, you've got to go. to the far corner, the furthest corner from the entrance. The purpose of that is not only to keep the milk cold, because the refrigeration is along the wall, but also to get you to walk through the store, preferably through as many aisles as possible. Because it's a staple, so they know you're going for milk and eggs and meats. So to have to walk through the entire

store to get there, then you go through all of that ultra-process stuff and all of the package stuff. It's great for your step counts. You mentioned something about camera research. This is so fascinating. When you say camera research, you mean the cameras that are in the store, but also the cameras that are in the self-checkout. Well, and also there are studies that are done where they put cameras where they watch customers and just watch what people do and set up different experiments within the store and check the way people respond to them. The purpose of a supermarket is to sell as much food as possible to as many people as possible, as often as possible, at as higher prices they can get away with. I can't say that enough. That's its purpose.

Okay, Marion, you identify three nutrition concepts that have emerged since your first run of what to eat in 2006. And those three things are the food systems have changed, ultra-processed foods, and try. triple duty diets. And I want to slow down and talk about all three. But I want to first have you give us a brief understanding of each. So in 2006, you wrote about processed foods. A few years later, we were introduced to ultra processed foods. Give us some examples of ultra processed foods. Just remind us of what's the difference. Oh, well, ultra processed is a specific category of food named by Carlos Montero, who's a public health professor in Brazil, who came up with the concept. And it's, these are industrially produced foods that contain large numbers of

color, texture and flavor additives that you don't necessarily have access to in supermarkets or in your home kitchen. And they're now associated, consumption of a lot of them is now associated in literally hundreds of studies with poor health outcome. Those are studies are observational and they cannot prove causation, but we now have very, very well-controlled clinical trials, at least three of them so far, that show that people who eat a lot of ultra-processed foods take in more calories than they otherwise would if they were eating unprocessed or minimally processed foods.

And the easiest example to explain the difference is corn on the cob is unprocessed, can corned is processed, and Doritos are ultra-processed. Mm-hmm. Okay. Yeah, they're designed to be irresistible, basically addictive. Like, you can't stop eating a bag of Doritos. You can't eat just one. One of the things that's so fascinating is you write that ultra-process foods are responsible for as much as a third of, of the environmental damage from food in wealthy countries? First of all, explain that, and why is that? Well, that has to do with the cost of production of the ingredients, plus the packaging, plus the waste,

plus everything that goes into taking a food, transforming it industrially, into something that doesn't look anything like the food to begin with. And then you've got all that packaging to do. deal with. I want to talk about the food system a little bit, too, because it's so relevant to this. The easiest way to describe the food system is, again, with corn. Because if you look at the 12 billion bushels of corn that are produced in the United States every year, roughly 45% of them of that corn is used to feed animals. Another 45% is used to make ethanol for automobiles.

And don't even get me started on that. I think it's just crazy. Leaving maybe 10% of the corn that's produced in the United States is food for people in all its forms. Not only corn on the cob, but corn ingredients, high-fructose corn syrup, all of that falls into that 10% category. We don't have a food system that's aimed at producing food for people. We have a food system that's aimed at producing feed for animals and fuel for automobiles. But the emphasis on animals is not very good for our environment because beef, the production of beef causes the largest release of greenhouse gases of any other food in the food system by a very large margin. So we would be much better off eating diets that had more plants and less animal,

not no animal necessarily, but certainly a lot less. And that's where the triple-duty dietary advice comes in because the diet that is best for preventing hunger, preventing obesity and its consequences, and preventing climate change is one in the same diet, which is to eat real food. processed as little as possible, with a big emphasis on plants. Right. Triple duty diets, it's a diet that simultaneously addresses hunger, obesity, and climate change. Yeah.

And it's the same diet as the one that's best for health. Isn't that nice? I mean, it's really, it's really, it all works out. You know, and easily, easily summarized by Michael Pollan in his famous seven words, Eat food, not too much, mostly plants. I took 700 pages to do the same thing. Well, I mean, okay, that solution seems clear. Eat more plants, eat less beef.

But you write that the American food supply provides twice as many calories at the same time as needed, while 40% of food produced is thrown away. And we're talking about this right as we also are understanding that there's global hunger. 800 million people face global hunger. So how do we talk seriously about triple-duty diets addressing food insecurity when the fundamental structure of our food system is designed to overproduce and waste food? Well, that's why I think food systems thinking is so important. Our food system in the United States produces 4,000 calories a day for every man, woman, and

little tiny baby in the country, that's roughly twice. what the population needs on average. So waste is built into the system. It's built. Why? Because that's how the subsidies work. The agricultural subsidies encourage food producers to produce as much food as possible because they get paid for the amount of food that they produce. 10% of the waste occurs at the supermarket level surprisingly little. Supermarkets have gotten really good. good at inventory control. They're very, very good at it, and there's very little supermarket waste. You think there's going to be a lot. They're going to be throwing away a lot of produce, but they really don't. And then 20% of it is at home, and that's something we can do something

about. But it's only a small part of the problem. It's a much bigger problem. It's a systems problem because it's built into the system. Is there a country or countries that have successfully implemented anything close to this triple duty dietary approach? Not that I can think of offhand. You know, the European, they're countries in Europe that can, they're much smaller than us. And they are somehow able to manage these kinds of things a lot better than we do. We have a lot to learn from countries in Europe along those lines and a lot to learn.

and a lot to learn from countries in Latin America about how to prevent obesity and its consequences through labeling rules and rules about marketing and that sort of thing. But we're Americans. We don't listen to anybody else. You have said something pretty astounding that's kind of been staying with me. I've heard you say this a couple of times that our food system is unfixable without a revolution. what would that revolution look like? Well, I think it would start with transforming our agricultural production system to one that was focused on food for people instead of animals and automobiles.

We would need to change our electoral system so that we could elect officials who were interested in public health rather than corporate health. We would need to fix our economy. so that Wall Street favors corporations who have social values and public health values as part of their corporate mission. Those are revolutionary concepts at this point because they seem so far from what is attainable. But I think if we don't work on that now, if we don't do what we can to advocate for a better food system,

We won't get it. And it's only if we advocate for it that we have a chance of getting it. And you never know. Sometimes you get lucky. Marian Nessel, it's been a pleasure to talk with you. Thank you so much. Thank you. Marian Nessel is the author of What to Eat Now.

In the new drama Hamnet, which is a new drama Hamnet, which is a food, now in theaters. Paul Meskell plays William Shakespeare as a young playwright, husband, and father, in the years leading up to his writing of Hamlet. The film, which also stars Jesse Buckley as Shakespeare's wife, was adapted from Maggie O'Farrell's 20-20 novel. It's the latest movie from Chloe Zau, the Oscar-winning director of Nomad Land. Our film critic Justin Chang has this review. In her moving 2020 novel, Hamnet, the Northern Irish writer Maggie O'Ferrell, explored the possibility that a real-life tragedy may have inspired one of the greatest fictional tragedies ever written.

William Shakespeare's son, Hamnet, died at the age of 11 in 1596, a few years before the first recorded performances of Hamlet at the Globe Theatre in London. From these facts, O'Farrell spun a historical fiction, a mix of research and speculation, into Shakespeare's personal life, starting with his rapturous. romance with a farmer's daughter, Anne Hathaway, the arrival of their three children, and the effect of Hamnett's death and Shakespeare's career on their marriage. Now O'Farrell has co-written an adaptation of her novel with the director Chloe Zhao, and it plays like a more somber and realistic version of Shakespeare in love. Call it Shakespeare in grief. The chief

focus isn't really Shakespeare at all, though he's sensitively played by Paul Meskell. The heart the movie is Anne, though here, as in certain historical documents, she's referred to as Agnes. She's played by an extraordinary Jesse Buckley. Agnes is a gifted healer, with a deep connection to the earth. She's most at home wandering the woods near her family's farmhouse in Stratford-upon-Avon. She falls into a passionate romance with William, who's tutoring her younger brothers in Latin, to help out his father, a struggling lovemaker. Anas becomes pregnant, to the chagrin of both families, especially William's mother, Mary, played by a strong Emily Watson.

Even so, the two lovers marry and settle down. Agnes gives birth to a daughter, Susanna. But before long, William, on the verge of becoming the most celebrated writer in the English language, is feeling boxed in by Sleepy Stratford. And so Anas selflessly sends him off to London, knowing he'll find the creative outlet he seeks there. William is thus away when she gives birth to their twins, Hamnet, and Judith. They enjoy a happy childhood, despite their father's long absences from home.

In this scene, William prepares to say the latest of many farewells to Hamnet, who's played by Jacoby Jopi Jop. Will we go with you this time? No, not yet. Hey. I'll miss you. But I have to go, you understand I. I know.

I understand. That's good. Because I need you to look after your mother and your sisters. Will you do that? Yes. Will you be brave? Yes. Yes.

Will you be brave? Yes. Will you be brave? Yes, yes, I'll be brave. I'll be brave. I'll be brave. After her clunky 2021 Marvel movie, Eternals, it's good to see Chloe Zhao back on firmer footing with Hamnet, though it isn't necessarily a film I'd have expected her to make. With its English period setting and real-life historical figures, it's a far cry from dramas like Nomadland and Songs My Brothers Taught me, which used a mix of fiction and non-fiction techniques to focus on little-scene corners of rural American life.

That said, there are echoes of the director's past work throughout Hamnet. William has some of the same vocational drivenness as, say, the rodeo cowboy we meet in Zhao's film, The Writer, determined to do what he was born to do. But William's time away from home takes a heavy toll on Agnes and their children, and Hamnet is, among other things, a tense portrait of marital estrangement. Agnes is, in many ways, a classic Zhao character, a woman deeply and eccentrically attuned to the natural world.

She also feels like an amalgam of some of Buckley's past roles, the wild child she played in the thriller Beast, but also the ill-treated girlfriends she played in mind-bending films like men, and I'm thinking of ending things. There's an elemental force to Buckley's performance in Hamnet. When Anyas gives birth, or watches as her son takes his last breath, she howls her agony to the skies. At some point, Buckley doesn't even seem to be acting anymore.

So effortlessly does she seem to inhabit Anya's earthy mysticism, her maternal love, and her bottomless grief and despair. She's the reason the film is as affecting as it is, especially at the climax, when we finally see how Shakespeare's son, Hamnet, and the first production of his play, Hamlet, converge. I'm still wrestling with what I think of this sequence, which will undoubtedly move audiences to tears. The first time I saw it, I shed more than a few myself. It's undeniably effective. It also feels a little reductive, in the way that it regards to it. guards an endlessly complex Shakespeare masterwork, in purely therapeutic terms, a means of

achieving closure. Zhao knows that in the end, the plays the thing. But as staged here, it feels like a smaller, less meaningful thing than it should. Justin Chang is a film critic for the New Yorker. He reviewed Hamnet. Coming up, science writer Mary Roach talks about the science of transplants. I'm Tanya Mosley, and this is Fresh Air Weekend. Here's Terry with our next interview. Here's the kind of questions my guest Mary Roach explores in her new book. What makes a pig a better organ donor than a goat? Could a heart survive indefinitely outside a body? How do you remove a deceased tissue donor's bones in a way the family will be comfortable with?

Her book titled Replaceable You is about the latest breakthroughs in replace. body parts from skin to hearts and prosthetic limbs. With advancements in regenerative medicine, stem cells, and genetic editing, dysfunctioning parts of our bodies are replaceable in ways that were previously impossible. Mary Roach also writes about attempts to replace body parts centuries ago, including false teeth in the George Washington era and nose replacements in the 1500s. Roach is known for her books about what makes the human body so remarkable, even the parts or functions we may find embarrassing or disgusting. She's also known for making her books funny and entertaining.

Mary Roach, welcome back to fresh air. So what led you to want to write about replacing body parts? Well, for one thing, I'm 66 and things are starting to go. So it's kind of ever present in my head. Also, with one exception, my books have always been about the human body. in some way, shape, or form. And so this was kind of a logical place to go at my age. But really, one of the things that triggered it was a conversation with a reader who had

contacted me with a book idea that didn't quite fit my interests. She wanted me to write about professional football referees. But it turned out, in the course of emailing with her, she's an amputee, specifically an elective amputee. She's somebody who she'd had spina bifida, her. foot was twisted. She couldn't walk well. She could walk but not well. She couldn't hike easily. And she would see people with a prosthetic lower limb walking, hiking, running. And she thought, well, I want that, but it was very difficult to find a surgeon to remove her foot because it

was quote unquote healthy. And she would say, yeah, but I can't walk on it. And I thought that was interesting, the reluctance of the surgeons to remove a foot because it is an act with some finality to remove a foot. Well, let's stick with that for a while. You write about how amputations aren't what they used to be. It's not like the guillotine amputation. You take like a knife or some kind of blade and like saw off the bones. I guess decapitates the wrong word, but I'll use it anyways, decapitate the limb. So what's different now? How has it done? Well, before there was anesthesia, time was the critical element. In other words, get it off. quickly. Don't be like slowly sawing. So now it's an operation that, you know, because the person

is out, it can be done carefully. And there are measures taken to try to preclude phantom limb pain. You can take nerves, the major nerves, and kind of wrap them around muscles so that they have something to do, basically. So they're not, in the words of one surgeon, a downed power line sparking in the roadway. So as a culture, one of the things we're starting to adjust to is the increasingly common use of animal parts to replace human parts. And I think one of the most common uses is the use of a pig's heart valve to replace a human's heart valve.

Why pigs? Well, you can, to a certain extent, blame Hormel, the pork company. What happened in the 40s, 50, 60s, there was a project that was a collaboration between the Mayo Clinic, the Mayo Foundation, which was the research arm of the Mayo Clinic, and the Hormel Institute, which was the research arm of pork. And the goal here was to create a smaller pig, a pig that would be a good match in terms of not just the size of human organs, but the functions. So all these studies were done looking at do pigs get coronary artery disease? And it turns out they do. In fact, the pig was described in one of their papers as a caricature of an obese human. In other words, gets heart disease, has heart issues, doesn't get enough exercise.

Why are those good things? Why does that make it more compatible with a human? Well, if you're going to study, if you're going to use the pig as your model, as you're a stand-in for a human, then you want to be sure that these organs do, that they behave similarly, that they're the similar size. So this research, once it got rolling, and there were dozens and dozens of papers, three volumes of papers looking at kidney function, liver function. There was one on orthodonture where they had put braces onto pigs. So it was all toward the goal of creating an analog, a stand-in for a human,

human being for trying out surgical techniques and, you know, replacements. So the pig, it became the go-to creature. I mean, there may be other animals. I mean, who knows, a goat might have been equally useful, but nobody started using goats. One of the big obstacles in transplanting organs, whether it's a human organ for a human being or an animal organ, is that the body rejects this foreign tissue, and the immune system thinks that this foreign tissue is like an invader that needs to be attacked. So the immune system starts attacking the organ that's saving your life. So how do they get around that with pig transplants? Yeah, with a organ that's coming from another species, the reaction is quite severe. It's called a

hyper-acute rejection where within minutes the body starts to attack, the organ starts to turn black. You don't want to put a pig organ into somebody without it having been genetically edited. So one of the things that's edited is something called the alpha-gal protein. And this is a surface protein that the body, if you can knock that out, you're basically just making the pig organ seem a little less pig-like and a little more human-like. So now you're dealing with a level of rejection that you would get with a human organ. If you keep kosher, like a lot of Jewish people do, you're not supposed to eat any, like, pig parts, no pork, no ham. Is a pig transplant considered kosher?

I asked this. I asked the surgeon who was involved in the first pig transplant. I said, who's Muslim. And he said, yeah, there are a lot of folks both in the Jewish religion and the Muslim religion who really wish we'd chosen a different species because I had been asking him, why pigs? And he said, I get that question all the time. The thing is, he said, we're not eating them. We are saving lives. So it's okay to get. get a pig organ if you're keeping kosher. And this was something that were interviews with various religious thought leaders. And there was consensus that it is indeed okay to have a pig organ implanted. Just don't eat it. So you write that the next step in terms of pig transplants is to try to grow human organs in pigs. I find that very hard to comprehend. So can you explain What the premise is? So do I. Okay.

This is way off in the future, but people are starting to look at it. The term is chimerism. In other words, a chimera being part two different creatures in one. So this would be, you would take a pig blastocysts, say, just a tiny cluster of cells, and you would edit it such that it's not going to produce, say, a kidney. and then you're introducing pluripotent human cells that could grow into a kidney so that this pig would literally be growing a human kidney within its body. And that kidney could then go to a person as a human kidney would.

And the pig, since it's always had that kidney, that human kidney, wouldn't reject it. So that's what we're talking about. it's obviously a long way off. There have been very, very primitive, like sort of bits of kidney that have been grown in an animal model, but this is not something coming along anytime soon. But really kind of interesting, because if you go fast forward, I don't know, a hundred years, the thinking would be that you could sort of have your own personal pig with a set of organs, kind of like having a car in the backyard for spare parts. You would have this pig with your organs ready to go when you need them.

Obviously, science fiction way, way out there, but people are working on chimerism. That's really amazing. It is, yeah. And I remember reading an ethics paper on the ethics of this, and they were saying, well, you know, some of the cells sometimes end up in other, parts of the animal's body, rather than just the kidney, say. So if they land in the brain such that the brain starts to develop more like a human brain, and the pig now starts to have human kind of awareness and intelligence, now do you need to treat the pig more like a human

with different, is there a moral obligation? I was like, whoo! That's a lot to wrap your head around. Yeah. I've never seen, I want to move on to 3D printers. I have never seen a 3D printer, and I've never seen the results of one, but there are experiments going on now using 3D printers for at least a phase of organ transplant. Would you explain how 3D printers are being experimented with now? Sure. I spent a day at the Feinberg Lab at Carnegie Mellon in Pittsburgh, and what people were working on there was, trying to print muscle in a way that the alignment of the cells would create muscle that had the specific function that muscle needed. In other words, a heart, the heart needs to move in a kind of a twisting motion. It twists as it pumps. So you've got to print the cells.

They have to be in a helix shape, which is different from, say, the hamstring, where it'd be kind of parallel or the shoulder muscle, they're in a kind of a fan-like shape, which gives you a lot of the versatility of the movement of the shoulder. So you're not just printing generic muscle. You have to print it in a very specific way to achieve the function that you want it to be doing, which I found kind of amazing. And no one is printing whole organs. That's way off in the future. But one of the people there had managed to print a single ventricle that was pumping in a mouse, which was, I mean, it doesn't sound like much. I think that's amazing. It is pretty amazing.

She said, though, because I said, oh, my God, you've got a ventricle pumping, keeping a mouse alive. She goes, whoa, whoa, whoa, the mouse still has his heart. But the blood is going through, and soon they're going to install. They had printed tri-leaflet valves that were. worked properly, which is amazing. You mentioned at the beginning of the interview that you're getting older and you feel like parts of your body are wearing up. And I'm wondering how the kind of books that you write that are so explicit about body

functions and about research into how the body works and this new book about new ways of like replacing organs, does that change your relationship to your own body? Does it make you more self-conscious about being in a body? Or has it made you more comfortable with your body? I like knowing more about what's going on in my body. And for the most part, it makes me appreciative, I guess. Like, I remember learning about stretch receptors and how you have these, you know, in the intestinal tract, in the rectum particular,

that got these receptors that know when this organ is stretching and filling and let your brain know. And I was like, that's how it works. So cool. So I am constantly marveling at all of this stuff going on in the background of myself. I think that I'm unpleasant to be around if you're at all squeamish. Why? Squeamish.

Well, okay, my husband is a very squeamish man, particularly as regards the eye. And I was reading this old booklet about, you know, the operation of couching where they press the lens down into the lower part of the eye. And he's like, X-Nay on the ouching, K, no. Like not, people aren't like me always. So sometimes I can't sort of share my appreciation for all these gooey bits and pieces of us that are performing miracles on a daily basis. there are some things that the body does as you put it in the background. And it's probably a good idea not to be too conscious of it. And I'm thinking of like digestion, what the large intestine is doing, what's passing through it, breathing. Like, unless you're like meditating or something,

or you have like breathing problems, if you're too conscious about your breathing without that consciousness having like some kind of function, it can be very distracting. It's best probably if you just do it. And there's all kinds of things. If you focus on it too much, it's easy to start worrying about it. Yes. There's something called heart awareness, where you become too aware of your heartbeat and what it's doing. And I think that creates anxiety, and then your heart does start doing it. I think, yes, it's not necessarily helpful to be tuned into all this. And I don't think that I am, I'm trying to think of an instance where I feel like I know too much. I know when I worked on Gulp.

About the digestive system. About everything between the nose and the butt, the weird tube with all the bacteria and everything. I became really aware of what's going on in your mouth when you chew, the process of bolus formation, where you're taking a piece of meat, say, and you're breaking it down, and then you're putting it back together in a bolus that's a shape that can slide down the throat. And I visited somebody who studies chewing and this process and what the jaws do. And I remember for a while after that going to restaurants and thinking, looking around at people chewing and swallowing and thinking,

this is disgusting. Like people should have sex in public. and eat in private. It's absolutely disgusting. One more question. There's a French expression, Bel Lad, I'm not sure exactly how to pronounce it, but it basically means beautiful, ugly,

which is, I think, a good way of describing a lot of parts of the body. There's something really like ugly and weird looking about some of the parts, the internal parts that we don't see, but there's something really magnificent and beautiful about it too. Do you feel that way about parts of the insides that we don't get to see? Very much so.

I mean, if you ever see a liver, well, you've seen a, I mean, No, I haven't seen a real, I've seen a chicken liver. A beef liver, say. Oh, I've seen that. It's a, it's kind of a glistening, streamlined, kind of beautiful object. It's not creepy, I don't think. And a heart, hearts are surprising. Like, if you see a heart inside somebody's chest beating.

And I saw this on an organ recovery. It's surprisingly active. I mean, you think from your own heartbeat that it's sort of a very gentle kind of motion. But that thing's like squirming around in there in this little space. It's kind of extraordinary. And it's doing that over and over and over and over for, like, if you're lucky, 80, 90, 100 years. And it keeps on going. And like, what thing that you buy at Best Buy keeps going that long?

It's the kind of thing I try not to think about a lot. don't think about it. Just let it do its thing and don't think about it. Yeah, yeah, yeah. Mary Roach, thank you so much for talking with us. It's always a pleasure to have you on the show. Thank you so much, Terry. Always a joy. Mary Roach's new book is titled Replaceable You, and she spoke with Terry Gross. Fresh Air Weekend is produced by Teresa Madden. Fresher's executive producer is Danny Miller. Our managing producer is Sam Brigger. Our technical director and engineer is Audrey Bentham.

With Terry Gross, I'm Tanya Mosley.